ATLANTA, Georgia (CNN) -- Americans claim to be savvy about sexually transmitted diseases, but knowing a few facts is not keeping them from taking many risks, according to a national survey.

The majority -- 84 percent -- of the survey respondents said they take necessary steps to prevent catching an STD, but 82 percent of the sexually active participants said they never use barrier protection when having oral sex. Almost half said they go without condoms when having vaginal sex.

"What we know is the right thing isn't what we often do," said Dr. James Allen, president of the American Social Health Association, the organization that conducted the survey and releases the findings Tuesday.

ASHA queried 1,155 adults between the ages of 18 and 35 for the survey. The effort was part of an educational initiative for April, which is Sexually Transmitted Diseases Awareness month.

"Part of the reason of the survey is to look for current information on what people are doing, what their risks are and what their level of knowledge is, " Allen said.

"And to look for disparities between level of knowledge and risk-taking behavior. In this instance the respondents on the survey said that they thought they had quite a bit of information about sexually transmitted diseases. And yet they did not act as though they knew that information."

Statistics indicate that one out of four Americans will contract a STD during their lifetime, but the more than two-thirds of survey participants expressed little concern about getting sexually transmitted diseases.

Among single, sexually active participants, almost three-quarters (71 percent) said they never use barriers when having oral sex, and 23 percent, nearly a fourth, never use condoms for vaginal sex, the survey found.

"One of the challenges that we have as we move forward in the early part of the 21st century is to understand how we can help people make the right choices to understand that they have real control of a lot of the health risks in their lives," Allen said.

Silence and stigma

Despite the risks and prevalence of sexually transmitted diseases, Allen said one of the most alarming findings in the study was adults' lack of communication about the topic.

More than 90 percent of respondents said they believed their current or recent sexual partner was disease free. But a third of them never discussed STDs with their partners and only half said their partners had been tested.

And while adults are making potentially fatal assumptions about their partners, they are also refraining from talking to medical professionals about STDs because of the stigma of appearing promiscuous or unclean.

"Often unless there is a specific problem they have to a possible STD, they do not bring it up," Allen said. "The physicians often don't ask about sexual function or what risky behaviors people are doing because it takes extra time and doctors themselves are sometimes not comfortable with talking about sex with their patients."

Almost 90 percent of survey participants said their physicians never recommended that they get vaccinated against hepatitis A and hepatitis B, the only sexually transmitted diseases for which there are vaccines. In fact, only about half of the respondents knew those diseases were transmitted sexually, the survey found.

"It is the whole environment that is created in the doctor-patient relationship, in that it is not really permissive on either side," Allen said. "Neither side is encouraging the other to talk about it."